Philonthus hepaticus (Coleoptera, Staphylinidae) in eastern Canada: are distribution gaps distinctive features or collecting artifacts?

Zookeys 22: 347-354 (2009) A peer-rev iewed open-access journal I
doi: 10.3897/zookeys.22.208 RESEARCH ARTICLE #ZooKey

www.pens oftonline.n et/zoo keys Launched to accelerate biodiversity research

Philonthus hepaticus (Coleoptera, Staphylinidae) in
eastern Canada: are distribution gaps distinctive
features or collecting artifacts?

Christopher G. Majka', Jean-Philippe Michaud’, Gaétan Moreau’, Ale’ Smetana?

I Research Associate, Nova Scotia Museum, 1747 Summer Street, Halifax, Nova Scotia, Canada 2 Université
de Moncton, Département de Biologie, Pavillon Rémi-Rossignol, Moncton, New Brunswick, Canada 3 Agri-
culture and Agri-food Canada, K. W. Neatby Bldg., Ottawa, Ontario, Canada

Corresponding author: Christopher G. Majka (c.majka@ns.sympatico.ca)

Academic editor: Jan Klimaszewski | Received 27 May 2009 | Accepted 30 June 2009 | Published 28 September 2009

Citation: Majka CG, Michaud J-P, Moreau G, Smetana A (2009) Philonthus hepaticus (Coleoptera, Staphylinidae)
in eastern Canada: are distribution gaps distinctive features or collecting artifacts? In: Majka CG, Klimaszewski J
(Eds) Biodiversity, Biosystematics, and Ecology of Canadian Coleoptera II. ZooKeys 22: 347-354. doi: 10.3897/
zookeys.22.208

Abstract

Philonthus hepaticus Erichson is reported for the first time in eastern Canada, and for only the second
time in Canada, from a specimen collected in New Brunswick. This discovery provides an opportunity to
examine apparent distribution gaps in the range of some rove beetles found in the Maritime Provinces of
Canada. Some of these gaps may be due to deficiencies in collecting effort, while others may result from
historic and prehistoric dispersal pathways, habitat fragmentation, or physiographic or climatic factors

that allow species to exist in areas beyond their primary geographic range.

Keywords
Coleoptera, Canada, New Brunswick, Staphylinidae, Staphylininae, Philonthus, range extensions, distri-

bution gaps

Introduction

The zoogeography of the Staphylinidae in Atlantic Canada is still imperfectly known,
and knowledge of this speciose family in the region is still actively developing. Some
Atlantic Canadian species exhibit striking apparent gaps in distribution. The Aleochari-

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348 Christopher G. Majka et al. | ZooKeys 22: 347-354 (2009)

nae are the most poorly known subfamily of the Staphylinidae, and as Majka and Kli-
maszewski (2008) pointed out, the confused and poorly understood systematics and
taxonomy of the group, their small size, the specialized microhabitats they inhabit, and
the external similarity of many species, have meant that they have been largely ignored
in many faunistic, zoogeographic, ecological, and taxonomic studies. Majka and Kli-
maszewski (2008) provided 94 new provincial and state records of 53 species of North
American aleocharines, which included many significant range extensions. Consequent-
ly, apparent distribution gaps in the range of most aleocharines may simply be an artifact
of collecting effort, or the lack of taxonomic resources to identify specimens.

However, even amongst the Staphylininae, arguably the best-known subfamily of
rove beetles in North America, there are Atlantic Canadian species that exhibit signifi-
cant distribution gaps. Some examples include Acylophorus caseyi Leng, which is known
from Halifax and Waverley, Nova Scotia, and is otherwise recorded in eastern Massachu-
setts (a distribution gap of 685 km); Hemiquedius ferox (LeConte), which is known from
Halifax and Crescent Beach, Nova Scotia, and is otherwise recorded in Paris, Maine
(550 km); Quedius spelaeus spelaeus Horn, which is known from several sites in Hants
County, Nova Scotia, and is otherwise recorded from Sullivan County, New York, (950
km) (Smetana 1965, 1971) (Fig. 1); Gabrius ulpius Smetana, which is known from the
Aspy River, Nova Scotia, and is otherwise recorded from Gorham, New Hampshire
(860 km); Philonthus rufulus Horn, which is known from Sable Island, Nova Scotia and
is otherwise recorded from southwestern Maine (880 km); and Philonthus thoracicus
(Gravenhorst), which is known from Kouchibouguac National Park, New Brunswick,

and is otherwise recorded in Paris, Maine (510 km) (Smetana 1995) (Fig. 2).

Results

In the present paper we add a further species to this roster, Philonthus hepaticus Erich-
son, 1840, on the basis of a specimen collected in Bouctouche, Kent County, New
Brunswick (46° 25’ 39.56" N, 64° 45’ 50.35” W) on 28 September 2007, by J.-P.
Michaud. ‘The specimen was recovered on a domestic pig (Sus scrofa Linnaeus) carcass
that had decomposed for 22 days in an agricultural field. For a comprehensive descrip-
tion of field characteristics and of the methods used to collect specimens, see Michaud
and Moreau (2009). This represents the first record of this species in eastern Canada,
and only the second Canadian record. The single previous Canadian record was a
specimen collected in Vancouver, British Columbia, 3 August 1956 by B.E and J.L.
Carr (Smetana 1995).

Discussion

In terms of the bionomics of the species, Smetana (1995: 179) wrote that, “Philonthus
hepaticus occurs in various kinds of rotting organic matter, such as dung (particularly

Philonthus hepaticus in eastern Canada: are distribution gaps distinctive features or collecting artifacts? 349

WV Acylophorus caseyi

© Hemiquedius ferox

@ Quedius s. spelaeus

Figure I. Distribution of Acylophorus caseyi, Hemiquedius ferox, and Quedius s. spelaeus in northeastern
North America [derived from Smetana (1971) and Moseley et al. (2006)].

horse and cow dung), rotting and fermenting fruit and vegetables, compost piles, grass
cuttings, etc. Specimens were also taken by sifting litter and other forest floor debris,
in seaweed and other beach debris and from litter along streams....”

In general, P hepaticus occurs across the United States from Massachusetts to
northern California, on an arc roughly south of 41° N latitude, south to the states of
Puebla and Veracruz in southern Mexico (19° N latitude). Consequently its discov-
ery in eastern New Brunswick, approximately 680 km north of central Massachusetts
where it has been previously recorded (Smetana 1995) is noteworthy (Fig. 3). This
initial record should be followed by further research to determine the extent of this
species’ distribution in the province.

Philonthus hepaticus is a fully macropterous species capable of flight. Smetana
(1995) noted that flight ability in the Philonthina is best developed in species that

350 Christopher G. Majka et al. / ZooKeys 22: 347-354 (2009)

Gabrius ulpius

Philonthus rufulus

Philonthus thoracicus

Figure 2. Distribution of Gabrius ulpius, Philonthus rufulus, and Philonthus thoracicus in northeastern
North America (derived from Smetana 1995).

are predaceous on insects and their larvae (particularly Diptera), which are found in
decompositional environments. Such species have sensitive olfactory chemoreceptors
for detecting byproducts of decomposition, and fly quickly and readily in search of
food. They are also ready crepuscular dispersers, and their highly developed flying
ability has (in part) been instrumental in the vast ranges exhibited by many species of
Philonthus. All this is likely to be true of P hepaticus; however, it is also the case that
with the exception of a couple of records (from British Columbia and Montana) the
entire range of this species lies south of 41° N latitude, apparently indicating that de-
spite the apparent dispersal abilities of this species, climatic, physiographic, ecological
or other factors have limited the nothward extend of its distribution. In this regard it is
noteworthy that the Northumberland Coastal Plain of the Atlantic Maritime Ecozone

Philonthus hepaticus in eastern Canada: are distribution gaps distinctive features or collecting artifacts? 351

% — Philonthus hepaticus

Figure 3. Distribution of Philonthus hepaticus in northeastern North America (derived from Smetana
1995)

(where Bouctouche is situated) has the highest mean summer temperatures (together
with isolated small pockets elsewhere), averaging + 19°C (1951-1980 values) of any
region in Atlantic Canada (McCalla 1988). Perhaps this is a contributing factor that
allows P hepaticus to survive in this area.

Philonthus hepaticus has in common with the rove beetles listed above, a distribu-
tion that apparently stops in central or northern New England, and then resumes in
the Maritime Provinces of Canada. In some instances, this distribution pattern may
be an artifact of collecting history, but in the case of some species such as Q. s. spelaeus
(Moseley et al. 2006) and P rufulus, these distribution gaps appear to reflect genuine
disjunctions and indicate populations isolated from the balance of the range of the spe-
cies. There are many examples of such species amongst other families of Coleoptera. A

gaz Christopher G. Majka et al. / ZooKeys 22: 347-354 (2009)

Cicindela marginipennis

Hyperaspis troglodytes
Diomus amabilis
Ephalus latimanus

Rypobius marinus

Figure 4. Nearest populations to Atlantic Canada of Cicindela marginipennis, Hyperaspis troglodytes, Di-
omus amabilis, Ephalus latimanus, and Rypobius marinus (derived from Leonard and Bell 1999; Majka et
al. 2008; Majka and Cline 2006; Majka and McCorquodale 2006; Sabine 2004).

few that illustrate the pattern include Diomus amabilis (LeConte), and Hyperaspis trog-
lodytes Mulsant [Coccinellidae] (Majka and McCorquodale 2006); Ephalus latimanus
(LeConte) [Tenebrionidae] (Majka et al. 2008); Rypobius marinus LeConte [Cory-
lophidae] (Majka and Cline 2006), and Cicindela marginipennis Dejean [Carabidae]
(Sabine 2004) (Fig. 4).

Majka and McCorquodale (2006) pointed out that some disjunct distributions in
this region are similar to those of the coastal plain element of the Nova Scotian flora,
plants which are found north to New England in the United States, whose distribution
then resumes in southern Nova Scotia. Keddy and Wisheu (1989) proposed that the
coastal plain flora arrived in southern Nova Scotia after the Wisconsinian glaciation by

Philonthus hepaticus in eastern Canada: are distribution gaps distinctive features or collecting artifacts? 353

migrating across Georges Bank to Browns Bank and thence to the mainland of the prov-
ince. Klimaszewski et al. (2006) discussed the role of offshore glacial refugia like Georges
Bank, and post-glacial island networks in the invertebrate colonization of Sable Island.
It is possible that some roves beetles with such disjunct distributions could have dis-
persed to the Maritime Provinces via this pathway, accounting for such observed distri-
bution patterns. Others may have dispersed to the region via continental pathways, and
have subsequently been isolated from the balance of their respective ranges by changing
environmental circumstances. Still others may not be disjunct at all (see below).

Are such disjunct distribution patterns real, or are they simply an artifact of collec-
tion effort? Only further research will resolve these questions. In particular, biodiver-
sity research on Coleoptera in the state of Maine, a key area in discerning the faunistic
relationships between New England and Atlantic Canada, has been fragmentary to
date. Some of these distribution gaps (i.e., for species such as Quedius s. spelaeus, Phi-
lonthus rufulus, Ephalus latimanus, and Cicindela marginipennis) are clearly not simply
artifacts of collecting effort. They may be a result of a variety of factors including
historic and prehistoric dispersal pathways, habitat fragmentation, and physiographic
or climatic factors that allow species to exist in areas beyond their primary geographic
range. Although many questions remain to be answered, such preliminary findings
point the way for profitable future biodiversity and zoogeographic research.

Acknowledgements

We thank Calum Ewing and Andrew Hebda for their assistance, and NSERC for fund-
ing the fieldwork.

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